twentyseventree is an octree extension for 3D and pseudo-3D

For a working putpixel method check out the scheme48-fb as a basis for
scsh images. You can get it at http://soft.vub.ac.be/~jceuppen/scheme/

fb stands for linux's framebuffer to draw on.

In the above scheme48-1.8-fb-x11 packages, X11 window drawing is supported.

Do read the packages' README files if you run into any problems.

-- Johan